Skip to main content

Full text of "Text Book Of Mechanical Engineering"

See other formats


Werder and Wicksteed Types.


weights j and lever H, the shorter arm of which is F, the pressure
being received on knife edges ^' apart (or much smaller than
shewn), and a leverage of 5bo to i thus obtained. A spirit level
is used to ascertain the horizontally of the lever H.

Professor Kennedy's Machine.ŚMessrs. Buckton & Co.
have made a machine to Professor Kennedy's requirements, em-
bodying the Werder principle with improvements. In Fig. 330,
A is the hydraulic ram in a fixed cylinder, and B a sliding frame
carrying an adjustable crosshead E, T shews a tension experiment
and c a compression experiment, the load being resisted in either
case by the crosshead F, and its effect transmitted throtigh the
rods GG to the system of levers. H corresponds to H in Fig. 329,
but a second lever M is here applied, with a jockey weight L to
avoid the trouble of changing weights. L is traversed by hand
gear at MX and carries a pointer at Q, while K' is a spring stop,
and j a hand gear for adjusting the position of *F by turning the
screws G G. In this machine all the operations are within control
of one experimenter and the specimen well in view; in addition
there is, during compression experiments, a shorter length of parts
between cylinder and weighing levers than in any other machine
(except the ' Emery'), as shewn by the thick lines in the figures
N, o, and P, thus giving less recoil on the knife edges at rupture.

The Wicksteed Machine, also by Messrs. Buckton, is
shewn at Fig. 331, as designed by Mr. Wicksteed to Professor
Unwin's instructions. A is the steelyard weighing lever, and B the
jockey weight, which at a leverage of 50 to i exerts 50 tons pull
upon the specimen. Additional weights up to ij tons at c exert
another 50 tons by means of 40 to i leverage. The knife edges
are shewn in detail at D, Fig. 332, being 20 inche^ long from
front to back; and the weight B is moved by screw #, either by
hand at E or by power at F, through the shaft b and gearing d,
the connection of the strap e being made immediately below the
fulcrum. Tfie levet is kept horizontally between stops H H by
admitting pressure Crater to the straining cylinder j through pipe
R, and the load is relieved towards the close of an experiment by
running back the jockey weight The pressure water is obtained
in Professor Kennedy's machine from the Hycbpaulic Power
Company, in a lat^r-built Wicksteed machine at the; Armstrong